The electrochemical oxidation of paper mill wastewater was studied using a dimensionally stable anode of composition Ti/RuPb(40%)Ox. The oxidation process was analyzed as a function of electrolysis time and with respe...The electrochemical oxidation of paper mill wastewater was studied using a dimensionally stable anode of composition Ti/RuPb(40%)Ox. The oxidation process was analyzed as a function of electrolysis time and with respect to the cell potential difference, electrolyte (NaCl) concentration, and pH of the sample. The purification of the effluent was evaluated through measurements of the removal of chemical oxygen demand (COD), color, and total polyphenols, and using UV-Vis spectroscopy. The results showed that the presence of NaCl is a determining factor in the purification process. Electrolysis of wastewater containing 5 g/L NaCl at a cell potential difference of 6 V for 120 min, removed 99% of COD and the percent removal values of color and polyphenols were 95% after 15 min of electrolysis. The UV-Vis spectrum showed evidence of the formation of hypochlorite ions (ClO-) during the electrolysis process, indicating that the electrochemical oxidation proceeds via an indirect mechanism with the participation of hypochlorite ions.展开更多
The effectiveness of ClO_2 bleaching as a replacement for conventional Cl_2 bleaching,which is intensively practiced in developing countries,to reduce polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs)in non...The effectiveness of ClO_2 bleaching as a replacement for conventional Cl_2 bleaching,which is intensively practiced in developing countries,to reduce polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs)in non-wood pulp and paper mills has not been field tested.The first field study was performed to investigate PCDD/F variations when ClO_2 bleaching was used as a substitute for conventional Cl_2 bleaching in a non-wood pulp and paper mill.It was found that the PCDD/F toxic equivalents(TEQs)in solid and effluent samples were approximately 1.3–14.9 times lower when ClO_2 bleaching was used instead of the conventional Cl_2 bleaching.2,3,7,8-Substituted tetrachlorinated dibenzofurans(2,3,7,8-TCDF)were the dominant contributors to total PCDD/F TEQs in samples from the investigated mill when using conventional Cl_2 bleaching.The formation amounts of 2,3,7,8-TCDF were reduced from 1.56–2.76 pg TEQ/g to 0.02–0.32 pg TEQ/g in solid samples when ClO_2 bleaching was used instead of the conventional Cl_2 bleaching.The replacement of Cl_2 with ClO_2 might decrease the chlorination reactions of dibenzofuran as potential precursors,and thus reduce the formation amounts of 2,3,7,8-TCDF.The results could provide important knowledge for suggesting the best available technique for PCDD/F reduction for non-wood pulp and paper mills in developing countries.展开更多
结合工程实际,采用桨叶式污泥干燥机对污泥进行干燥,采用鼓泡式流化床焚烧炉对污泥和纸渣进行焚烧处理,研究了干燥焚烧系统的污染物排放,以及焚烧过程中煤的混烧与否对污染物排放的影响.研究发现,污泥干燥过程将释放出烷烃、苯和低级脂...结合工程实际,采用桨叶式污泥干燥机对污泥进行干燥,采用鼓泡式流化床焚烧炉对污泥和纸渣进行焚烧处理,研究了干燥焚烧系统的污染物排放,以及焚烧过程中煤的混烧与否对污染物排放的影响.研究发现,污泥干燥过程将释放出烷烃、苯和低级脂肪酸等易挥发性有机气体以及NH3、HCl和HCN等无机污染气体.在导热油温为180℃时,干燥水蒸气的冷凝液化学需氧量(COD)为113.6 mg/L.混煤燃烧后常规污染物和二恶英的排放浓度均显著降低,CO质量浓度由574.8 mg/m3降至144.5 mg/m3,二恶英国际当量浓度由0.144 ng I-TEQ/m3降至0.04 ng I-TEQ/m3;将焚烧飞灰进行重金属渗滤液浓度检测,其结果远低于国家标准GB 5085.3—1996规定的危险废物浸出液最高允许浓度值.展开更多
文摘The electrochemical oxidation of paper mill wastewater was studied using a dimensionally stable anode of composition Ti/RuPb(40%)Ox. The oxidation process was analyzed as a function of electrolysis time and with respect to the cell potential difference, electrolyte (NaCl) concentration, and pH of the sample. The purification of the effluent was evaluated through measurements of the removal of chemical oxygen demand (COD), color, and total polyphenols, and using UV-Vis spectroscopy. The results showed that the presence of NaCl is a determining factor in the purification process. Electrolysis of wastewater containing 5 g/L NaCl at a cell potential difference of 6 V for 120 min, removed 99% of COD and the percent removal values of color and polyphenols were 95% after 15 min of electrolysis. The UV-Vis spectrum showed evidence of the formation of hypochlorite ions (ClO-) during the electrolysis process, indicating that the electrochemical oxidation proceeds via an indirect mechanism with the participation of hypochlorite ions.
基金support provided by the National 973 program (No. 2015CB453100)the Youth Innovation Promotion Association CAS (No. 2016038)the Strategic Priority Research Program of the CAS (No. XDB14020102)
文摘The effectiveness of ClO_2 bleaching as a replacement for conventional Cl_2 bleaching,which is intensively practiced in developing countries,to reduce polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs)in non-wood pulp and paper mills has not been field tested.The first field study was performed to investigate PCDD/F variations when ClO_2 bleaching was used as a substitute for conventional Cl_2 bleaching in a non-wood pulp and paper mill.It was found that the PCDD/F toxic equivalents(TEQs)in solid and effluent samples were approximately 1.3–14.9 times lower when ClO_2 bleaching was used instead of the conventional Cl_2 bleaching.2,3,7,8-Substituted tetrachlorinated dibenzofurans(2,3,7,8-TCDF)were the dominant contributors to total PCDD/F TEQs in samples from the investigated mill when using conventional Cl_2 bleaching.The formation amounts of 2,3,7,8-TCDF were reduced from 1.56–2.76 pg TEQ/g to 0.02–0.32 pg TEQ/g in solid samples when ClO_2 bleaching was used instead of the conventional Cl_2 bleaching.The replacement of Cl_2 with ClO_2 might decrease the chlorination reactions of dibenzofuran as potential precursors,and thus reduce the formation amounts of 2,3,7,8-TCDF.The results could provide important knowledge for suggesting the best available technique for PCDD/F reduction for non-wood pulp and paper mills in developing countries.
文摘结合工程实际,采用桨叶式污泥干燥机对污泥进行干燥,采用鼓泡式流化床焚烧炉对污泥和纸渣进行焚烧处理,研究了干燥焚烧系统的污染物排放,以及焚烧过程中煤的混烧与否对污染物排放的影响.研究发现,污泥干燥过程将释放出烷烃、苯和低级脂肪酸等易挥发性有机气体以及NH3、HCl和HCN等无机污染气体.在导热油温为180℃时,干燥水蒸气的冷凝液化学需氧量(COD)为113.6 mg/L.混煤燃烧后常规污染物和二恶英的排放浓度均显著降低,CO质量浓度由574.8 mg/m3降至144.5 mg/m3,二恶英国际当量浓度由0.144 ng I-TEQ/m3降至0.04 ng I-TEQ/m3;将焚烧飞灰进行重金属渗滤液浓度检测,其结果远低于国家标准GB 5085.3—1996规定的危险废物浸出液最高允许浓度值.
